1. Field of the Invention
The present invention relates to a process for the production of patterned decorative materials having a coating exhibiting artistic crepe-like relieved patterns, namely, patterns of wrinkled and relieved textural appearance caused by different local shrinkages of the coated paint layer.
2. Description of the Prior Art
Processes have hitherto been known for producing pattern decorative materials having a coating exhibiting three dimensional relief patterns. For example, a process is proposed in the Japanese Patent Publication No. 57073/1986, on column 5, lines 9-28, in which a substrate material is first coated with a vinyl chloride sol paint and the coating layer is subjected, after baking the coating, to a processing by press rolling using an embossing roller to form thereon embossed patterns. In the Japanese Patent Publication No. 54470/1986, from line 23 on column 2 to line 6 on column 3, and in the Japanese Patent Publication No. 54471/1986, from line 22 on column 2 to line 5 on column 3, another technique is described in which a substrate material is coated with a paint having a resin component composed of a vinyl chloride resin including a pulverous thermoplastic resin using a coating roller in such a manner that the coating layer obtained involves a regularly repeating thickness variation to form a riffled or striped embossed pattern.
As to the wrinkle paint for producing a crepe-like pattern, those which have a resin component consisting of a modified alkyd resin obtained with a drying oil having unsaturated double bond, such as, China wood oil, oiticica oil or so on, and containing a considerable amount of dryer consisting of an organic salt of cobalt or manganese have found hitherto their practical applications [Cf. the Japanese magazine "Toso-Gijutsu" April, p. 45 (1964)].
A further technique has been proposed in which a wrinkle paint is prepared using, as the essential resin component, cellulose acetate butyrate resin, an epoxy resin and a urea resin together with an acid catalyst and an amine catalyst ["Official Digest" March, p. 298-310 (1962)].
These prior art techniques for producing patterned decorative material having a coating with embossed patterns exhibit, however, disadvantages. For example, in the process employing an embossing roller, an additional procedure for preparing embossed patterns is required, resulting thus in an increase in the production costs, and, in addition, the coating layer becomes thin at the corner of each embossment caused from the sharp cant thereof, bringing about a weakening of the coating and a reduction of the strength to external aggressive influences at such portions. In the process using a paint containing vinyl chloride resin having incorporated therein a pulverous thermoplastic resin, a thickness of the coating layer of 150-250 .mu.m in the protruding areas is required for attaining a three dimensional feeling by the embossed patterns, whereby the productivity becomes lower and the production costs are high. In the case of employing vinyl chloride resin, a plasticizer is incorporated in general. Plasticizers are subject to aging, whereby the coating layer will, in general, become harder after a prolonged period of time.
In the case of using the conventional wrinkle paint with the drying oil having an unsaturated double bond, a relatively thick coating layer is required for attaining a sufficient performance of the coating layer and for obtaining preferable crepe-like patterns. It is necessary to cause the coating layer to harden up to the internal bulk thereof by placing the coated article in an oven maintained at a temperature of 60.degree.-100.degree. C., after almost all the low boiling solvent has been volatilized off, whereupon the temperature of the heating box is raised up to 100.degree.-150.degree. C. after 10-20 minutes where crepe-like patterns have been formed over the entire surface. In addition, the paint is apt to form coverage skin layer during storage, requiring thus a sufficient caution for its storage and filtration should be incorporated before practical use of the paint for removing the coverage skin layer. Furthermore, the paint after storage for a long period of time develops crepe-like patterns only with difficulty and they are inferior in the strength against external aggressive influences and in the weatherability.
In the case of wrinkle paint having as the main components cellulose acetate butyrate resin, an epoxy resin and an urea resin, together with an acid catalyst and amine catalyst, a thickness of the coating layer of more than about 100 .mu.m is necessary for obtaining acceptable crepe-like patterns. The mutual reaction due to the employment of an epoxy resin, an acid catalyst and an amine catalyst renders the storage stability of the paint inferior, so that it cannot be stored over 9 weeks. Moreover, the weatherability of the paint is quite inferior due to the employment of epoxy resin.
When these conventional wrinkle paints are coated on a substrate directly, textural artistic relief patterns cannot be obtained, even though a crepe-like pattern uniformly developed over the whole surface may be formed.